Check this one too :
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1950266069&category=11713
...thought that I've had a chance getting the whole (HP25) kit at a yard sale in Bedford, MA last summer for $37.00.
How about this one ?
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1951050759&category=3294
Ouff ! Time to stock them up :)